* [PATCH] rcu: init and destroy rcu_synchronize when necessary
@ 2020-04-15 22:26 Wei Yang
2020-04-16 0:24 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Wei Yang @ 2020-04-15 22:26 UTC (permalink / raw)
To: paulmck, josh; +Cc: rcu, linux-kernel, Wei Yang
We would skip the rcu_synchronize if it is a duplicate call back function.
This is not necessary to init and destroy for them.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
kernel/rcu/update.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 6c4b862f57d6..91e44b527aad 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -353,13 +353,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
might_sleep();
continue;
}
- init_rcu_head_on_stack(&rs_array[i].head);
- init_completion(&rs_array[i].completion);
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
+ init_rcu_head_on_stack(&rs_array[i].head);
+ init_completion(&rs_array[i].completion);
(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
+ }
}
/* Wait for all callbacks to be invoked. */
@@ -370,9 +371,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
wait_for_completion(&rs_array[i].completion);
- destroy_rcu_head_on_stack(&rs_array[i].head);
+ destroy_rcu_head_on_stack(&rs_array[i].head);
+ }
}
}
EXPORT_SYMBOL_GPL(__wait_rcu_gp);
--
2.23.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rcu: init and destroy rcu_synchronize when necessary
2020-04-15 22:26 [PATCH] rcu: init and destroy rcu_synchronize when necessary Wei Yang
@ 2020-04-16 0:24 ` Paul E. McKenney
2020-04-16 21:44 ` Wei Yang
0 siblings, 1 reply; 3+ messages in thread
From: Paul E. McKenney @ 2020-04-16 0:24 UTC (permalink / raw)
To: Wei Yang; +Cc: josh, rcu, linux-kernel
On Wed, Apr 15, 2020 at 10:26:55PM +0000, Wei Yang wrote:
> We would skip the rcu_synchronize if it is a duplicate call back function.
>
> This is not necessary to init and destroy for them.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Applied, thank you!
I edited the commit log a bit. Could you please check below to make
sure that I didn't mess anything up?
Thanx, Paul
------------------------------------------------------------------------
commit d9eaddf545fe8e3e2725e2fa0bf87b59b5667c14
Author: Wei Yang <richard.weiyang@gmail.com>
Date: Wed Apr 15 22:26:55 2020 +0000
rcu: Initialize and destroy rcu_synchronize only when necessary
The __wait_rcu_gp() function unconditionally initializes and cleans up
each element of rs_array[], whether used or not. This is slightly
wasteful and rather confusing, so this commit skips both initialization
and cleanup for duplicate callback functions.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 3ce63a9..351c322 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -391,13 +391,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
might_sleep();
continue;
}
- init_rcu_head_on_stack(&rs_array[i].head);
- init_completion(&rs_array[i].completion);
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
+ init_rcu_head_on_stack(&rs_array[i].head);
+ init_completion(&rs_array[i].completion);
(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
+ }
}
/* Wait for all callbacks to be invoked. */
@@ -408,9 +409,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
break;
- if (j == i)
+ if (j == i) {
wait_for_completion(&rs_array[i].completion);
- destroy_rcu_head_on_stack(&rs_array[i].head);
+ destroy_rcu_head_on_stack(&rs_array[i].head);
+ }
}
}
EXPORT_SYMBOL_GPL(__wait_rcu_gp);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rcu: init and destroy rcu_synchronize when necessary
2020-04-16 0:24 ` Paul E. McKenney
@ 2020-04-16 21:44 ` Wei Yang
0 siblings, 0 replies; 3+ messages in thread
From: Wei Yang @ 2020-04-16 21:44 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: Wei Yang, josh, rcu, linux-kernel
On Wed, Apr 15, 2020 at 05:24:00PM -0700, Paul E. McKenney wrote:
>On Wed, Apr 15, 2020 at 10:26:55PM +0000, Wei Yang wrote:
>> We would skip the rcu_synchronize if it is a duplicate call back function.
>>
>> This is not necessary to init and destroy for them.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>
>Applied, thank you!
>
>I edited the commit log a bit. Could you please check below to make
>sure that I didn't mess anything up?
>
Yep, the changelog looks good to me :-)
Glad you like it.
> Thanx, Paul
>
>------------------------------------------------------------------------
>
>commit d9eaddf545fe8e3e2725e2fa0bf87b59b5667c14
>Author: Wei Yang <richard.weiyang@gmail.com>
>Date: Wed Apr 15 22:26:55 2020 +0000
>
> rcu: Initialize and destroy rcu_synchronize only when necessary
>
> The __wait_rcu_gp() function unconditionally initializes and cleans up
> each element of rs_array[], whether used or not. This is slightly
> wasteful and rather confusing, so this commit skips both initialization
> and cleanup for duplicate callback functions.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>
>diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
>index 3ce63a9..351c322 100644
>--- a/kernel/rcu/update.c
>+++ b/kernel/rcu/update.c
>@@ -391,13 +391,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
> might_sleep();
> continue;
> }
>- init_rcu_head_on_stack(&rs_array[i].head);
>- init_completion(&rs_array[i].completion);
> for (j = 0; j < i; j++)
> if (crcu_array[j] == crcu_array[i])
> break;
>- if (j == i)
>+ if (j == i) {
>+ init_rcu_head_on_stack(&rs_array[i].head);
>+ init_completion(&rs_array[i].completion);
> (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
>+ }
> }
>
> /* Wait for all callbacks to be invoked. */
>@@ -408,9 +409,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
> for (j = 0; j < i; j++)
> if (crcu_array[j] == crcu_array[i])
> break;
>- if (j == i)
>+ if (j == i) {
> wait_for_completion(&rs_array[i].completion);
>- destroy_rcu_head_on_stack(&rs_array[i].head);
>+ destroy_rcu_head_on_stack(&rs_array[i].head);
>+ }
> }
> }
> EXPORT_SYMBOL_GPL(__wait_rcu_gp);
--
Wei Yang
Help you, Help me
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2020-04-16 0:24 ` Paul E. McKenney
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